Model Store list: resource-group selector and card filtering by available resource group

## Background

On the user-facing Model Store list page (`react/src/pages/ModelStoreListPageV2.tsx`), add a resource-group selector so users see only the model cards relevant to the resource groups they can actually deploy on. This reduces wrong selections across heterogeneous accelerators.

## Requirements

- Add a **resource-group selector** to the Model Store list page (reuse `BAIProjectResourceGroupSelect` from `backend.ai-ui`).
- **Before** a resource group is selected: show only model cards deployable on the resource groups available in the current project.
- **After** a resource group is selected: show only cards deployable on that resource group.

## Backend dependency

Blocked on backend. `projectModelCardsV2` (scope `ProjectModelCardV2Scope`, filter `ModelCardV2Filter`) currently exposes no resource-group filter. A backend field to filter model cards by resource-group availability is required before this can be implemented end-to-end.

## Acceptance Criteria

- [ ] Resource-group selector present on the list page.
- [ ] Card set filtered by the available / selected resource group(s).
- [ ] `TODO(needs-backend)`: resource-group filter on `projectModelCardsV2`.

## Affected files

- `react/src/pages/ModelStoreListPageV2.tsx`

JIRA Issue: FR-3122